In the medical diagnosis of certain internal organs, extensive use is made today of a so-called endoscope by which the internal surface of organs within a body cavity, e.g., the lower intestine, urethra, esophagus, and other such elongated internal organs may be observed through the insertion of the elongated part of the endoscope. In addition to diagnosis, certain treatments can be affected through the use of instruments having an elongated insertible portion.
In the use of such insertible portions of the endoscope, a requirement is that the insertible portion be substantially centered within the body cavity of interest known as the lumen in that, where the insertible element is not centered, the path of advance of the insertible part may be blocked and, in the process, pain or injury may be caused to the patient. Accordingly, a long felt need in the art has been that of a method of advancing the insertible portion of the endoscope in a manner which maintains the inserted portion substantially at the center of the body cavity to be examined.
The present invention makes use of sectors within a defined polar coordinate grid system and a comparison of the light level (known as the gray level) of such sectors relative to certain references. Algorithmic parameters provide a means for continual centering of the insertible end of the endoscope within the lumen.
Numerous mechanical systems, involving servo-driven mechanisms have been known in the art as, for example, is reflected in U.S. Pat. Nos. 4,787,369 (1980) to Allred and U.S. Pat. No. 4,941,454 (1990) to Wood et al. These, and many other electro-mechanical systems, are directed to steerable catheters..Also, endoscopes may be advantageously employed in connection with control information provided by the instant invention in order to achieve real time centering of the head of the endoscope or catheter as it is advanced within the body lumen of interest. The use of computers in monitoring the operation of an endoscope is known in the art, as is reflected in U.S. Pat. No. 4,742,815 (1988) to Ninan et al, entitled Computer Monitoring of Endoscope. Also, the use of gray scale calibrated sectors in controlling the direction of an endoscope is taught in U.S. Pat. No. 4,910,590 (1990) to Gillies et al, entitled Endoscope Insertion Direction Detection Method. The instant invention differs from that of Gillies in that the primary purpose of the instant invention is to control centering of the endoscope, in that state-of-the-art methods of controlling longitudinal and other movements of an endoscope are satisfactory in most applications. Further, the technology of Gillies is far more complex than the method of centering taught herein and, as such, the instant inventive system and method can be made available to a far greater population in need of such diagnostic and treatment equipment because of the economics associated therewith.
A further reference is U.S. Pat. No. 5,018,509 (1991) to Suzuki et al, entitled Endoscope Insertion Controlling Apparatus. Suzuki differs from the instant invention in its use of an algorithm that calls for the use of three generally oval shaped concentric regions in which the relative gray-scale values thereof are compared. Also, Suzuki relies upon a pattern recognition program. Further, Suzuki continually makes use of a system having one-thousand pixels at each edge of the screen. Thereby one million pixels and, in support thereof, a corresponding amount of computer memory is necessary in the operation of the Suzuki system. The present invention, as is more particularly set forth below, makes use of a system of 136 sectors defined in terms of polar coordinates about an origin point, after the initial scan-in of data. The algorithms and related software necessary to implement the inventive system involves comparisons involving only the said 136 sectors, this as compared to the potential need to compare information within one million pixels in the Suzuki system. Further, the Suzuki system does not make use of the entire visual observing field of an endoscope, this being a requirement of the particular algorithm employed by Suzuki.